Circuit breaker arm



April 1956 F. w. HARTMAN, JR

CIRCUIT BREAKER ARM Filed Nov. 8, 1951 Frqnli I I/I Hartman J2:

IN V EN TOR.

CIRCUIT BREAKER ARM Frank W. Hartman, Jr., Dearborn, Mich., assignor to Holley Carburetor Company, Detroit, Mich., a corporation of Michigan Application November 8, 1951, Serial N 0. 255,443 1 Claim. (Cl. 200-30) The object of this invention is to facilitate the service on a circuit breaker arm for an ignition system now in universal use on automobiles. At the moment, whenever a circuit breaker lever is badly worn, even though its tungsten point is intact, the whole lever is thrown away. If the insulated rubbing block could be detached and replaced, a considerable saving could be made. This is not commercially possible with present construction. I have discovered that a rotatable, detachable roller of nylon is the answer, and a spring carried by the circuit breaker arm permits the worn rubbing block to be removed and to be replaced.

Figure 1 is a plan view of the preferred form of my invention. Figure 2 is a partial view in elevation.

In the figure, 10 is the pivot on which the circuit breaker arm 12 oscillates. This arm is made of a stamping. 14 is the movable tungsten contact. 11 is the stationary contact (ground) carried on an ear 27 from the plate 17 which forms the support for the pivot 10. 16 is the spring which holds the contact 14 so that it engages with its corresponding stationary contact 11 when the circuit is made. This spring 16 is also the conductor leading the current from the connection 15 to the contact 14. 18 is the insulation surrounding the pin 10. 20 is a hollow nylon roller which is retained by two ribs 22 and 24 stamped integral with the arm 12 so that the roller cannot escape sideways. An abutment 26 acts as a backstop and a flat spring 28 holds the roller 20 in place. Obviously, the roller will slowly rotate as the device operates. As the roller rotates, wear is spread over its entire circumference. The plate 17 is secured to the cir- United States Patent 2,740,853 ?atented Apr. 3, 1956 cuit breaker plate 49 by two screws 19 and 21, which are loosened and tightened to adjust the timing, but these parts are no part of this invention, which is specifically directed to the circuit breaker aim 12 and its insulated nylon roller 20 as a separate service part installed in the distributors as a replaceable element in servicing a car.

Operation The nylon roller 20 is engaged by the cam 23 driven by the shaft 25 which is driven at one-half engine speed The wear of the rotating roller 20 is sufficiently slow so that the life of the unit is determined by the burning of the tungsten contact points 14-11. If the rubbing block 20 wears faster than the contacts 1114 burn, eventually the contacts fail to open and the engine ceases to run. It is true that by loosening the screws 19 and 21, the contacts can be readjusted; however, meanwhile an embarrassing situation has developed. The less the wear, the longer the life; as if the tungsten points 1114 do burn slightly faster than the roller 20 wears, the result is not particularly objectionable-it merely reduces the period during which the coil and the condenser are charged.

What I claim is:

In a device of the character described having a stationary contact and a movable contact and a lever supporting the movable contact, a support therefor, a spring engaging said lever, a movable contact carried on the end of the lever, the novel feature which includes a detachable rotating cylindrical rubbing block adapted to be pressed against the lever by said spring, an abutment located on the lever adapted to locate the rubbing block, a second spring mounted on the lever and adapted to press the rubbing block against said abutment, and to permit said cylindrical block to rotate and in which the lever is made in the form of a channel and the cylindrical rubbing block is laterally restrained by the arms of said channel.

References Cited in the file of this patent UNITED STATES PATENTS 984,564 Holt et al. Feb. 21, 1911 1,356,532 Lang Oct. 26, 1920 2,246,922 Macchioni June 24, 1941 2,623,131 Chermendy Dec. 23, 1952 

